Heat-treating apparatus with roller-type hearth

ABSTRACT

The ceramic hearth rollers of a kiln are connected to driving and supporting shafts by pin-and-slot connections which enable universal pivoting and lengthwise expansion and contraction of the rollers relative to the shafts while reducing the danger of the ends of rollers becoming chipped and broken during service use.

United States 1atent 1111 3,608,876

[72] Inventors Charles E. Leaich [56] References Cited Rockford; UNITEDSTATES PATENTS L-springermlvidmbmh 1,777,921 10/1930 Hudson 263/6c x AW-27,339 1,992,467 2 1935 Blythe 263/6C [22] hled Apr. 10,1970 2045 773 63 I 63 d Se t 28 1971 /l9 6 Havey 1 1 2 [6C [451 ff d d C 2,156,395 51939 Klouman 263/6C [731 Abbgm 2,986,386 5/1961 Trimborn. 263/6C3,006,625 10/1961 Boron 263/6c Primary ExaminerCharles J. MyhreAttorney-Wolfe, Hubbard, Leydig, Voit 81 Osann [54] HEAT'TREATINGAPPARATUS WlTH ROLLER' ABSTRA C'll: The ceramic hearth rollers of a kilnare con- TYPI? nected to driving and supporting shafts by pin-and-slotcon- 7 cla'mssDrawmg nections which enable universal pivoting andlengthwise ex- [52] U.S.Cl 263/6C pansion and contraction of the rollersrelative to the shafts [Sl] lnt.Cl.... F27b 9/24 while reducing thedanger of the ends of rollers becoming [50] Field of Search 263/6, 6 Cchipped and broken during service use1 y r *1 I r 1 .1 I 11 1 49 i-a"-eer 1: 11 I M Jd if g Ill HEAT-TREATING APPARATUS WITH ROLLER-TYPEHEAR'II-I BACKGROUND OF THE INVENTION This invention relates toimprovements in heat-treating apparatus and more particularly relates toapparatus for mounting and driving a series of sideby-side rollersadapted to be power rotated to convey workpieces through a work chamber,The rollers are rotatably supported between the sidewalls of the workchamber and usually are formed of ceramic material capable ofwithstanding the high temperatures prevailing in the chamber. Apparatusof this general type is shown in US. Pat. No. 3,338,569.

SUMMARY OF THE INVENTION The primary aim of the present invention is tomount and drive the rollers in a new and comparatively simple mannerwhich results in the individual rollers being positively rotated at alltimes, which accommodates lengthwise expansion and contraction of therollers as the latter are heated and cooled, and which, at the sametime, enables universal pivoting of the rollers relative to theirsupporting shafts while reducing the danger of the ends of the rollersbeing damaged during such pivoting.

In a more detailed sense, the invention resides in achieving theforegoing through the provision of a novel pin-and-slotuniversal-driving connection between the end of each roller and a shaftfor rotatably supporting the roller, the shaft preferably including aprotective cup telescoped over the roller and prevented by thepin-and-slot connection from hottoming against and damaging the end ofthe roller.

These and other objects and advantages of the invention will become moreapparent from the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary side elevationof an exemplary heattreating apparatus having rollers which are drivenand supported in accordance with the present invention.

FIG. 2 is an enlarged fragmentary cross section taken substantiallyalong the line 2-2 of FIG. 1.

FIG. 3 is an enlarged side elevation of parts shown in FIG. 1, portionsof the view being broken away and shown in section.

FIG. 4 is an enlarged fragmentary cross section taken substantiallyalong the line 4-4 of FIG. 3.

FIG. 5 is an enlarged fragmentary view of parts illustrated in FIG. 4and showing the pin-and-slot connection between the end of one of therollers and the supporting shaft for such roller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT For purposes ofillustration, the invention is shown in the drawings in conjunction witha heat-treating apparatus in the form of a roller hearth kiln having aheated work chamber 11 (FIG. 2) within which workpieces I3 are heated tohigh temperatures. The workpieces are conveyed into, through and out ofthe chamber by a series of side-by-side rollers 14 spanning the chamberand adapted to be power rotated to advance the workpieces.

The work chamber 11 is defined by upright sidewalls l5 and I6 (FIG. 2),a bottom wall 17 and a top closure 19 all made of refractory materialand suspended from a framework consisting partly of I-beams 20 locatedabove and suspended from a framework consisting partly of I-beams 20located above and extending transversely of the chamber and supported onupright posts 2I (FIG. I). Preferably, the rollers 14 are disposed onlMi-inch centers within the chamber and are arranged in groups of 30,some of the rollers of the first group being located outside of theentrance end (the left end as viewed in FIG. I) of the chamber for thepurpose of'conveying the workpieces I3 into the chamber. Additionalgroups of rollers (not shown) are supported outside of the exit end ofthe chamber to carry the workpieces away from the chamber.

As shown most clearly in FIG. 2, the hearth rollers M which are disposedwithin the chamber 11 are mounted for rotation and for endwise slidingwithin openings 23 in the sidewalls I5 and 16 and project outwardlybeyond the sidewalls. The openings are packed with fibrous insulatingmaterial 24 in order to retard the flow of heat to the outboard end ofthe rol' lers, the latter preferably being tubular, being made ofceramic material and being packed with insulation 25 (FIG. 4).

The present invention contemplates coupling the rollers I4 to drivingand supporting shafts 26 and 27 (FIG. 4) by uniquely arrangedpin-and-slot connections 30 which coact with the shafts to effect apositive rotational drive to each roller, to allow unrestrictedexpansion and contraction of the roller during heating and cooling ofthe roller, and to enable universal pivoting of the roller relative tothe shafts in the event the shafts and the ends of the roller aremisaligned. The pin-andslot connections are particularly characterizedby their ability to enable driving and pivoting of the rollers withoutthe ends of the rollers becoming chipped or broken.

In the present instance, each driving shaft 26 (FIG. 4) comprises anelongated cylindrical member disposed outside of the chamber 111 at theleft end of the respective roller 14 and journaled for rotation in ballbearings 31 mounted in a pair of parallel sideplates 33 and 34. Thelatter are suspended by uprights 35 from a rail 36 anchored to andextending beneath the I-beams 20. Several pairs of sideplates aredisposed endto-end outside of the sidewall 25 of the chamber and eachpair extends alongside the ends of a group of thirty rollers.

To rotate the rollers 14 for purposes of advancing the workpieces 13, amotor 37 (FIG. 1) is located on the sideplates 33 near the center of thekiln I0 and drives a series of gearboxes 40 which are connected to oneanother by shafts 41 and couplings 43. Each gearbox 40 serves to rotatea group of 30 rollers and each is supported on one of the outersideplates 33. Chains 44 and 45 (FIGS. 3 and 4) are trained around drivesprockets 46 and 47 on the output shaft 49 of each gearbox and serve torotate sprockets 50 and SI, respectively, which are connected to theindividual driving shafts 26, the chains being guided around thesprockets S0 and SI by idler sprockets 53 (FIG. 4) disposed between thesideplates. The sprockets 50 are fastened to the driving shafts 26 ofalternate ones of the rollers in the group of 30 and are set outwardlyfrom the sprockets SI which are fastened to the driving shafts of theremaining rollers in the group. With the chains 44 and 45 thus rotatingalternate rollers, every other roller will continue to be rotated toadvance the workpieces 13 through the chamber Ill in the event that oneof the chains should break. In addition, the offsetting of the sprockets50 and 51 from one another enables the use of larger sprockets inconjunction with the closely spaced rollers and also enables the use ofmore rugged drive chains.

Each supporting shaft 27 is mounted for rotation and for endwise slidingin ball bearings 55 (FIG. 4) which are supported by a pair of sideplates56 and 57, the latter being arranged along the right side (FIG. 2) ofthe chamber 111 outside of the sidewall 16 and being connected touprights 59 hung from a rail 60 extending beneath the I-beams 20. Likethe plates 33 and 34, several pairs of the plates 56 and 57 are disposedend-to-end outside of the chamber and each pair is associated with agroup of 30 rollers.

Advantageously, each supporting shaft 27 is biased toward its respectiveroller 14 so as to accommodate lengthwise expansion and contraction ofthe roller as the latter is heated and cooled. For this purpose, a coilspring 61 (FIG. 4) is telescoped over each supporting shaft and iscompressed between the outer sideplate 56 and a collar 63 secured to theshaft. Thus, the springs urge the supporting shafts to slide in-. wardlywithin the bearings 55 and toward the rollers. Herein, the supportingshafts and the inner races of the bearings 55 are formed withcomplementary hexagonal or other noneircular cross sections so that thesupporting shafts may slide axially within the bearings whilestillturning the inner races within the outer races so as to take fulladvantage of the antifriction characteristics of the bearings.

Preferably, a protective cup 65 (F lGS. 4 and 5) is welded to theinboard end of each driving and supporting shaft 26 and 27 and istelescoped over the adjacent end of the roller 14. The rollers and cupsfit loosely with one another so as to leave the rollers free to floatradially within the cups, each cup, for example, having an insidediameter of about 1-1] 16 inches and each roller being approximately 1inch in diameter although rollers and cups of various different diameterdiameters may be used.

The pin-and-slot connections 30 serve to couple the rollers 14 and thecups 65 for rotation in unison and for relative pivoting whilepreventing the ends of the rollers from engaging and breaking againstthe closed ends 66 of the cups. As shown most clearly in FIG. 5, eachconnection comprises an elongated key or pin 67 anchored to andextending radially of the cup intermediate the ends thereof. Each pin isreceived in a pair of elongated and diametrically opposed U-shaped slots69 formed in and extending axially of the roller and opening out of theoutboard end of the roller. In this instance, each pin has a diameter ofapproximately five thirty-seconds of an inch while the slots have awidth of approximately three sixteenths of an inch thus establishingradial clearance between the pin and the edges of the slots to enablethe end of the roller to float within the cup. importantly, each pin 67and each set of slots 69 are positioned axially of the roller such thatthe distance a (for example, one-fourth of an inch) between the outboardend of the roller and the closed or axially facing ends 70 of the slotsis considerably less than the distance b (for example, seven-sixteenthsof an inch) between the closed end 66 of the cup 65 and the innersurface of the pin 67. In this way, the pin will bottom against theslots and prevent the end of the roller from bottoming against and beingchipped or broken by the closed end of the cup when the roller is in apivoted position within the cup.

With the foregoing arrangement, each spring 61 acting on its respective,supporting shaft 27 tends to slide the latter inwardly relative to thebearings 55 to press the pin 67 on the end portion of the shaft 27 intoseating engagement with the closed ends 70 of the slots 69 in theadjacent end of the roller 14. The roller, in turn, is urged to the left(FIG. 4) to press the closed ends of the slots in the opposite end ofthe roller against the pin 30 carried on the driving shaft 26. As theroller expands lengthwise during heating, the spring yields to allowsuch expansion to occur without mechanically overstressing the roller.Of course, when the roller subsequently contracts and shortens, thespring relaxes to keep the pins pressed firmly against the closed endsof the slots. The spring tends to place the roller in a state ofcompression at all times and, since ceramic material is comparativelystrong in compression while being weak in tension, the possibilities ofthe roller being broken are reduced.

The rotational movement of each driving shaft 26 is transmitted to therespective roller 14 by the pin 67 on the end portion of the shaftengaging the edges of the slots 69 in the adjacent end of the roller.Being located in the deepest portion of the slots and pressed againstthe closed ends 70 thereof, the pin bears and drives against the moststructurally rugged part of the slots and thus there is less likelihoodof the extreme ends of the roller adjacent the slots being chipped awaythan would be the case if the pin were located intermediate the ends ofthe slots and nearer to the outer end of the roller. Also, the drivingpin tends to engage the curved closed end of each slot face-to-face todistribute the driving force over a greater area of the slot (asindicated schematically by the stress pattern shown in FIG. 5) thanwould be possible with line-to-line contact between the pin and theslot.

Because the rollers 14 and the pins 67 fit loosely in the cups 65 andthe slots 69, respectively, each roller may pivot within its respectivecup to accommodate any minor parallel or angular misalignment that mightexist between the shafts 26 and 27 for such roller. Preferably, the pinsat the opposite ends of each roller are disposed at right angles to oneanother as shown in FIG. 4 to facilitate pivoting of the roller withinthe cups with a universal action. As a result of the relative locationsof the pins 67, the closed ends 70 of the slots 69 and the closed ends66 of the cups 65, the extreme ends of each roller are held out ofengagement with the closed ends of the cups to reduce the danger of theroller ends being broken by the cups during pivoting of the roller.

It will be appreciated by those skilled in the art that pin-andslotconnections different from the connections 30 specifically shown may beused in carrying out the invention. For example, the pins 67 may becarried by the rollers 14 and fit into either slots or enlarged recessesformed in the protective cups 65 when such cups are employed.Alternatively, other types of telescoping arrangements may be usedbetween the rollers and the shafts 26 and 27 with the pins carried byone of the telescoped end portions of the members and bottomed againstslots formed in the other of the telescoped end portions.

We claim as our invention:

1. A heat-treating apparatus having opposed walls defining a workchamber, and a series of side-by-side rollers for supporting workpiecesspanning said chamber and adapted to be power rotated to convey theworkpieces through the chamber, the improvement in said apparatuscomprising, means in said walls mounting said rollers for rotation andfor endwise sliding within said chamber, elongated shafts disposed atopposite ends of each roller and journaled for rotation adjacent saidwalls, at least one of said shafts for each roller being powerrotatedand at least one of said shafts being mounted for endwise sliding, meansyieldably biasing said slidable shafts toward said rollers, a cupcarried on the inboard end of each shaft and telescoped slidably overthe outboard end of the adjacent roller with a loose fit, a connectionbetween the telescoped end portions of each cup and roller for couplingthe cups and the rollers together for rotation .in unison whilepermitting pivoting of the rollers within the cups, each of saidconnections comprising a pin anchored to and extending radially throughsaid cup and fitted loosely within an elongated slot formed in andextending axially of the outer end portion of said roller so as to leavethe roller free for pivoting within the cup, each of said slots havingan axially facing closed end pressingly engaging the associated pin byvirtue of the bias applied to said slidable shaft and having an oppositeopen end opening out of the outboard end of the roller, and the distancebetween the closed end of each slot and the outboard end of theassociated roller being less than the distance between each pin and theclosed end of the adjacent cup thereby to prevent the outboard ends ofthe rollers from engaging the closed ends of the cups.

2. A heat-treating apparatus having opposed walls defining a workchamber, and a series of side-by-side rollers for supporting workpiecesspanning said chamber and adapted to be power rotated to convey theworkpieces through the chamber, the improvement in said apparatuscomprising, means in said walls mounting said rollers for rotation andfor endwise sliding within said chamber, elongated shafts disposed atopposite ends of each roller and journaled for rotation adjacent saidwalls, at least one of said shafts for each roller being power rotatedand at least one of said shafts being mounted for endwise sliding, meansyieldably biasing said slidable shafts toward said rollers, a cupcarried on the inboard end of each shaft and telescoped slidably overthe outboard end of the adjacent roller with a loose fit, a connectionbetween the telescoped end portions of each cup and roller for couplingthe cups and the rollers together for rotation in unison whilepermitting pivoting of the rollers within the cups, each of saidconnections comprising a key carried by and extending radially of one ofthe telescoped end portions and fitted loosely within a recess formed inthe other of the telescoped end portions so as to leave the telescopedend portions free for relative pivoting, each of said recesses having anedge facing axially of the associated roller and pressingly engaging theassociated key by virtue of the bias applied to said one shaft, and saidedges and said keys being located axially of said rollers in positionspreventing the outboard ends of said rollers from engaging the closedends of said cups.

3. A heat-treating apparatus as defined in claim 2 in which the keys onopposite ends of each roller are disposed substantially at right anglesrelative to one another.

4. A heat-treating apparatus as defined in claim 2 in which each of saidrecesses comprises an axially extending slot formed in one of saidtelescoped end portions and opening out of the end of such end portion.

5. A heat-treating apparatus as defined in claim 2 in which each of saidkeys comprises a pin anchored to and extending radially of itsrespective cup, each of said recesses comprising an axially extendingslot formed in the end portion of said roller, each of said slots havinga closed end defined by said axially facing edge and having an open endopening out of the outboard end of the roller.

6. A heat-treating apparatus as defined in claim 5 in which the distancebetween the closed end of each slot and the outboard end of theassociated roller is less than the distance between each pin and theclosed end of the adjacent cup thereby to prevent the outboard ends ofthe rollers from en- 7 gaging the closed ends of the cups.

7. A heat-treating apparatus having a series of side-by-sidc rollers forsupporting workpieces and adapted to be power rotated to advance theworkpieces, the improvement in said apparatus comprising, elongatedsupporting members telescoped loosely with opposite ends of each rollerand journaled for rotation adjacent said rollers, at least one of saidsupporting members for each roller being power rotated and at least oneof said supporting members being mounted for end wise sliding, meansyieldably biasing said slidable supporting members toward said rollers,a pin-and-slot connection between the telescoped end portions ofeachroller and supporting member for coupling the rollers and thesupporting members together for rotation in unison while permittingpivoting of the rollers relative to the supporting members, each of saidconnections comprising a pin carried by and extending radially of one ofthe telescoped end portions and fitted loosely within a slot formed inand extending axially of the other of the telescoped end portions so asto leave the telescoped end portions free for relative pivoting, andeach of said slots having an open end opening out of the end of itsrespective telescoped end portion and having an opposite closed endfacing axially of said roller and located in pressing engagement withthe associated pin.

1. A heat-treating apparatus having opposed walls defining a workchamber, and a series of side-by-side rollers for supporting workpiecesspanning said chamber and adapted to be power rotated to convey theworkpieces through the chamber, the improvement in said apparatuscomprising, means in said walls mounting said rollers for rotation andfor endwise sliding within said chamber, elongated shafts disposed atopposite ends of each roller and journaled for rotation adjacent saidwalls, at least one of said shafts for each roller being power-rotatedand at least one of said shafts being mounted for endwise sliding, meansyieldably biasing said slidable shafts toward said rollers, a cupcarried on the inboard end of each shaft and telescoped slidably overthe outboard end of the adjacent roller with a loose fit, a connectionbetween the telescoped end portions of each cup and roller for couplingthe cups and the rollers together for rotation in unison whilepermitting pivoting of the rollers within the cups, each of saidconnections comprising a pin anchored to and extending radially throughsaid cup and fitted loosely within an elongated slot formed in andextending axially of the outer end portion of said roller so as to leavethe roller free for pivoting within the cup, each of said slots havingan axially facing closed end pressingly engaging the associated pin byvirtue of the bias applied to said slidable shaft and having an oppositeopen end opening out of the outboard end of the roller, and the distancebetween the closed end oF each slot and the outboard end of theassociated roller being less than the distance between each pin and theclosed end of the adjacent cup thereby to prevent the outboard ends ofthe rollers from engaging the closed ends of the cups.
 2. Aheat-treating apparatus having opposed walls defining a work chamber,and a series of side-by-side rollers for supporting workpieces spanningsaid chamber and adapted to be power rotated to convey the workpiecesthrough the chamber, the improvement in said apparatus comprising, meansin said walls mounting said rollers for rotation and for endwise slidingwithin said chamber, elongated shafts disposed at opposite ends of eachroller and journaled for rotation adjacent said walls, at least one ofsaid shafts for each roller being power rotated and at least one of saidshafts being mounted for endwise sliding, means yieldably biasing saidslidable shafts toward said rollers, a cup carried on the inboard end ofeach shaft and telescoped slidably over the outboard end of the adjacentroller with a loose fit, a connection between the telescoped endportions of each cup and roller for coupling the cups and the rollerstogether for rotation in unison while permitting pivoting of the rollerswithin the cups, each of said connections comprising a key carried byand extending radially of one of the telescoped end portions and fittedloosely within a recess formed in the other of the telescoped endportions so as to leave the telescoped end portions free for relativepivoting, each of said recesses having an edge facing axially of theassociated roller and pressingly engaging the associated key by virtueof the bias applied to said one shaft, and said edges and said keysbeing located axially of said rollers in positions preventing theoutboard ends of said rollers from engaging the closed ends of saidcups.
 3. A heat-treating apparatus as defined in claim 2 in which thekeys on opposite ends of each roller are disposed substantially at rightangles relative to one another.
 4. A heat-treating apparatus as definedin claim 2 in which each of said recesses comprises an axially extendingslot formed in one of said telescoped end portions and opening out ofthe end of such end portion.
 5. A heat-treating apparatus as defined inclaim 2 in which each of said keys comprises a pin anchored to andextending radially of its respective cup, each of said recessescomprising an axially extending slot formed in the end portion of saidroller, each of said slots having a closed end defined by said axiallyfacing edge and having an open end opening out of the outboard end ofthe roller.
 6. A heat-treating apparatus as defined in claim 5 in whichthe distance between the closed end of each slot and the outboard end ofthe associated roller is less than the distance between each pin and theclosed end of the adjacent cup thereby to prevent the outboard ends ofthe rollers from engaging the closed ends of the cups.
 7. Aheat-treating apparatus having a series of side-by-side rollers forsupporting workpieces and adapted to be power rotated to advance theworkpieces, the improvement in said apparatus comprising, elongatedsupporting members telescoped loosely with opposite ends of each rollerand journaled for rotation adjacent said rollers, at least one of saidsupporting members for each roller being power rotated and at least oneof said supporting members being mounted for endwise sliding, meansyieldably biasing said slidable supporting members toward said rollers,a pin-and-slot connection between the telescoped end portions of eachroller and supporting member for coupling the rollers and the supportingmembers together for rotation in unison while permitting pivoting of therollers relative to the supporting members, each of said connectionscomprising a pin carried by and extending radially of one of thetelescoped end portions and fitted loosely within a slot formed in andextending axially of the other of the telescoped end portions so aS toleave the telescoped end portions free for relative pivoting, and eachof said slots having an open end opening out of the end of itsrespective telescoped end portion and having an opposite closed endfacing axially of said roller and located in pressing engagement withthe associated pin.